Peripheral blood tyrosinase messenger RNA detection and survival in malignant melanoma

USP22 deficiency in melanoma mediates resistance to T cells through IFNγ-JAK1-STAT1 signal axis

Genome-wide clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated 9 (Cas9)-mediated loss-of-function screens are powerful tools for identifying genes responsible for diverse phenotypes. Here, we perturbed genes in melanoma cells to screen for genes involved in tumor escape from T cell-mediated killing. Multiple interferon gamma (IFNγ) signaling-related genes were enriched in melanoma cells resistant to T cell killing. In addition, deletion of the deubiquitinating protease ubiquitin specific peptidase 22 (USP22) in mouse melanoma (B16-OVA) cells decreased the efficacy of T cell-mediated killing, both in vitro and in vivo, while overexpression enhanced tumor-cell sensitivity to T (OT-I) cell-mediated killing. USP22 deficiency in both mouse and human melanoma cells showed impaired sensitivity to interferon pathway and USP22 was positively correlated with key molecules of interferon pathway in clinical melanoma samples. Mechanistically, USP22 may directly interact with signal transducer and activator of transcription 1 (STAT1), deubiquitinate it, and improve its stability in both human and mouse melanoma cells. Our findings identified a previously unknown function of USP22 and linked the loss of genes in tumor cells that are essential for escaping the effector function of CD8⁺ T cells during immunotherapy.

Circulating Tumor Cells and Early Relapse in Node-positive Melanoma

PURPOSE

There is a need for sensitive, reproducible biomarkers for patients with stage III melanoma to guide clinical decision making. Circulating tumor cells (CTCs) can be detected in patients with melanoma; however, there are limited data regarding their significance in stage III disease. The aim of this study was to determine whether CTCs are associated with early relapse in stage III melanoma.

EXPERIMENTAL DESIGN

We prospectively assessed CTCs at first presentation in clinic (baseline) for 243 patients with stage III melanoma. CTCs were measured using the CellSearch System. Relapse-free survival (RFS) was compared between patients with one or more baseline CTC versus those with no CTCs. Log-rank test and Cox regression analysis were applied to establish associations of CTCs with RFS.

RESULTS

At least one baseline CTC was identified in 90 of 243 (37%) patients. Forty-five (19%), 67 (28%), 118 (49%), and 13 (5%) patients were stage IIIA, IIIB, IIIC, or IIID, respectively. CTC detection was not associated with substage, or primary tumor characteristics. Multivariable analysis demonstrated that the detection of ≥1 baseline CTC was significantly associated with decreased 6-month RFS [log-rank, P < 0.0001; HR, 3.62, 95% confidence interval (CI), 1.78-7.36; P < 0.0001] and 54-month RFS (log-rank, P = 0.01; HR, 1.69; 95% CI, 1.13-2.54; P = 0.01).

CONCLUSIONS

≥1 CTC was independently associated with melanoma relapse, suggesting that CTC assessment may be useful to identify patients at risk for relapse who could derive benefit from adjuvant therapy.

Circulating Tumor Cells in Stage IV Melanoma Patients

BACKGROUND

Management of stage IV melanoma patients remains a challenge. In spite of promising new therapies, many patients develop resistance and progression. The aim of this pilot study was to determine if circulating tumor cells (CTCs) are associated with shortened (180-day) progression-free survival (PFS) after a baseline CTC assessment in stage IV melanoma patients.

STUDY DESIGN

A baseline CTC assessment was performed in 93 stage IV melanoma patients using a commercially available immunomagnetic system. The presence of 1 or more CTC was considered a positive result. A Cox multivariable regression model was used to evaluate the association between presence of CTCs at baseline and PFS, after adjusting for covariables. Kaplan-Meier curves and a log-rank test were used to summarize and compare unadjusted PFS for patients stratified by CTC positivity.

RESULTS

Median follow-up was 17 months; mean age was 55 years. Thirteen of 93 (14%) patients had no evidence of disease (NED) at baseline CTC assessment. One or more CTC was detected in 39 of 93 (42%) of patients at baseline; CTCs were not associated with primary melanoma features or NED status. Twenty-eight of 93 (30%) patients progressed within 180 days of baseline draw, with 20 of 39 (51%) of the CTC-positive patients relapsing compared with 8 of 54 (15%) of the CTC-negative patients. In adjusted Cox models, a significant association was found suggesting worse PFS within 180 days for CTC-positive patients at baseline (vs CTC-negative) (hazard ratio 4.69, 95% CI 1.59 to 13.77, p = 0.005).

CONCLUSIONS

One or more CTCs at baseline were associated with progression within 180 days in stage IV melanoma patients. This information warrants further study of CTCs as a means of identifying patients at high-risk for disease progression.

Detection of circulating melanoma cells in the blood of melanoma patients: a preliminary study

Significant prognostic heterogeneity exists within the substages of melanoma; therefore, novel prognostic biomarkers are needed to provide information on the risk of recurrence. Limited available data suggest prognostic significance for circulating melanoma cells (CMCs); there is a need for a sensitive, reproducible, and standardized identification technique. Using a semiautomated technology, we sought to determine whether CMCs could be identified reliably in stage I-IV melanoma patients and whether the presence of CMC correlated with known prognostic factors. CMCs were detected in the peripheral blood (7.5 ml) of patients with stage I-IV melanoma (n=89) using the CellSearch system. CD146 cells were immunomagnetically enriched; nucleated HMW-MAA/CD45/CD34 cells were considered CMCs. One or more CMCs was detected in 45% of all patients, varying with stage of disease (stages I/II, III, and IV: 35, 44, and 86%, respectively; P=0.03, for stage I/II vs. stage IV); 55% had one CMC, 32% had two CMCs, and 13% had three or more CMCs identified. The presence of CMCs in the blood was associated with histologic subtype, particularly in patients with stage I/II disease (superficial spreading 18% vs. acral lentiginous 75%). Using a semiautomated technique, CMCs can be identified in a significant number of melanoma patients. These data support further study with longer follow-up and longitudinal/serial time points to better determine the identification rates and prognostic significance of CMCs in stage I-IV melanoma patients.

Kinetic and sensitive analysis of tyrosinase activity using electron transfer complexes: in vitro and intracellular study

Tyrosinase is an important marker of human diseases such as the neurodegeneration associated with Parkinson's disease and melanoma. Sensitive detection of tyrosinase activity in vitro and inside cells is of great significance to medical diagnostics and skin disorder treatments. With unique photophysical properties, semiconductor quantum dots (QDs) are employed as photoluminescent platforms for various biosensing, in particular for the detection of enzyme activities. In this work, QDs are functionalized with tyrosine and zwitterionic molecules to construct a nanometer-scale scaffold (QD-Tyr conjugate), and this is used to test tyrosinase activity in vitro and inside cells. Tyrosinase oxidizes tyrosine to dopachrome and switches on the electron-transfer access, which relates to fluorescence quenching. High quenching efficiency is achieved by shortening the distance between the electron donors and acceptors, which is attributed to the small size of the conjugated tyrosine. Enzymatic process curves reveal the enhanced enzymatic activity on the conjugated nanoparticle substrate, which leads to highly sensitive detection of tyrosinase (as low as 1 nM). It is also demonstrated that QD-Tyr conjugates can sensitively probe intracellular tyrosinase in melanoma cells, which promises great potential in disease monitoring and medical diagnostics.

An electrochemical immunosensing method for detecting melanoma cells

An electrochemical immunosensing method was developed to detect melanoma cells based on the affinity between cell surface melanocortin 1 receptor (MC1R) antigen and anti-MC1R antibody (MC1R-Ab). The MC1R-Abs were immobilized in amino-functionalized silica nanoparticles (n-SiNPs)-polypyrrole (PPy) nanocomposite modified on working electrode surface of screen-printed electrode (SPE). Cyclic voltammetry was employed, with the help of redox mediator ([Fe(CN)6](3-)), to measure the change in anodic oxidation peak current arising due to the specific interaction between MC1R antigens and MC1R-Abs when the target melanoma cells are present in the sample. Various factors affecting the sensor performance, such as the amount of MC1R-Abs loaded, incubation time with the target melanoma cells, the presence of interfering non-melanoma cells, were tested and optimized over different expected melanoma cell loads in the range of 50-7500 cells/2.5 mL. The immunosensor is highly sensitive (20 cells/mL), specific, and reproducible, and the antibody-loaded electrode in ready-to-use stage is stable over two weeks. Thus, in conjunction with a microfluidic lab-on-a-chip device our electrochemical immunosensing approach may be suitable for highly sensitive, selective, and rapid detection of circulating tumor cells (CTCs) in blood samples.

Diagnostic accuracy of circulating tumor cells detection in gastric cancer: systematic review and meta-analysis

BACKGROUND

Circulating tumor cells (CTCs) detection has previously been used for diagnosing gastric cancer. However, the previous studies failed to make an agreement whether the detection of CTCs contributes to the diagnosis of gastric cancer.

METHODS

A systematic review and meta-analysis was performed to evaluate the overall accuracy of CTCs detection for diagnosing gastric cancer. PubMed, Embase and the Wanfang database were searched in all languages published up to Oct 2012. The pooled sensitivity (SEN), specificity (SPE), positive and negative likelihood ratios (PLR and NLR, respectively), diagnostic odds ratio (DOR) and summary receiver operating characteristic (sROC) curve were calculated to evaluate the overall test performance.

RESULTS

Twenty studies were included in this systematic review and meta-analysis. The diagnostic value of CTCs detection for the gastric cancer was calculated to evaluate the overall test performance. The summary estimates of The pooled sensitivity, specificity, positive and negative likelihood ratios, diagnostic odds ratio were 0.42 (95% confidence interval (CI), 0.21-0.67), 0.99 (95% CI, 0.96-1.00), 58.2 (95% CI, 9.8-345.9), 0.58 (95% CI, 0.38-0.89), and 100 (95% CI, 15-663), respectively. The summary receiver operating characteristic curve was 0.97 (95% CI, 0.95-0.98). Deek's funnel plot asymmetry test found no evidence of study publication bias in the current study (P = 0.49).

CONCLUSION

This systematic review suggests that CTCs detection alone cannot be recommended as a screening test for gastric cancer. However, it might be used as a noninvasive method for the confirmation of the gastric cancer diagnosis.

Prognostic value of microphthalmia-associated transcription factor and tyrosinase as markers for circulating tumor cells detection in patients with melanoma

The aim of this study was to analyze microphthalmia-associated transcription factor (MITF) as a marker for the detection of circulating melanoma cells, determine its prognostic value in melanoma patients, and compare it with tyrosinase. Blood samples from 201 melanoma patients in all stages of the disease and 40 healthy volunteers were analyzed. RNA was isolated from mononuclear cell fraction of the blood and assayed by reverse transcription-PCR for the expression of MITF and tyrosinase. All samples from healthy volunteers were negative for both MITF and tyrosinase. Out of 201 blood samples from melanoma patients 32 were positive for MITF, 20 for tyrosinase, and four for both MITF and tyrosinase. Analysis of MITF as an additional marker to tyrosinase allowed for detection of circulating melanoma cells in a larger number of melanoma patients in comparison to tyrosinase analysis alone (48 vs. 20 positive). A positive value of MITF was associated with shorter progression-free (P=0.005) and overall survival (P=0.042). A positive value of tyrosinase was associated with shorter overall survival (P=0.012), whereas there was no significant association between the value of tyrosinase and progression-free survival. The value of MITF was selected with multivariate analysis as the independent prognostic factor for progression-free survival, whereas the only independent prognostic factor for overall survival was the stage of disease. This study has shown that MITF is a specific marker for detection of circulating melanoma cells that has a prognostic value in melanoma patients. Determination of MITF in addition to tyrosinase improved the detection of circulating melanoma cells in melanoma patients.

Melanoma biomarkers: Vox clamantis in deserto (Review)

Detecting malignant melanoma at an early stage, monitoring therapy, predicting recurrence and identifying patients at risk for metastasis continue to be a challenging and demanding objective. The last two decades have witnessed innovations in the field of melanoma biomarkers. However, global agreement concerning monitoring and early detection has yet to be reached. This is a review of the current literature regarding melanoma biomarkers including demographic, clinical, pathological and molecular biomarkers that are produced by melanoma or non-melanoma cells. A number of these biomarkers demonstrate promising results as possible methods for early detection, predicting recurrence and monitoring therapy. Other biomarkers appear to be promising for identifying patients at risk for metastasis. We reviewed the most pertinent information in the field thus far and how this knowledge can impact, or not, the management of melanoma patients prognostically and therapeutically.

Issues affecting molecular staging in the management of patients with melanoma

Prediction of metastatic potential remains one of the main goals to be pursued in order to better assess the risk subgroups of patients with melanoma. Detection of occult melanoma cells in peripheral blood (circulating metastatic cells [CMC]) or in sentinel lymph nodes (sentinel node metastatic cells [SNMC]), could significantly contribute to better predict survival in melanoma patients. An overview of the numerous published studies indicate the existence of several drawbacks about either the reliability of the approaches for identification of occult melanoma cells or the clinical value of CMC and SNMC as prognostic factors among melanoma patients. In this sense, characterization of the molecular mechanisms involved in development and progression of melanoma (referred to as melanomagenesis) could contribute to better classify the different subsets of melanoma patients. Increasing evidence suggest that melanoma develops as a result of accumulated abnormalities in genetic pathways within the melanocytic lineage. The different molecular mechanisms may have separate roles or cooperate during all evolutionary phases of melanocytic tumourigenesis, generating different subsets of melanoma patients with distinct aggressiveness, clinical behaviour, and response to therapy. All these features associated with either the dissemination of occult metastatic cells or the melanomagenesis might be useful to adequately manage the melanoma patients with different prognosis as well as to better address the different melanoma subsets toward more appropriate therapeutic approaches.

Circulating tumor cells as prognostic factor for distant metastases and survival in patients with primary uveal melanoma

PURPOSE

The aim of this study was to determine in patients with high-risk primary uveal melanoma whether the detection of circulating tumor cells by quantitative reverse transcription-PCR (RT-PCR) is of prognostic relevance.

EXPERIMENTAL DESIGN

Blood samples from 110 patients with high-risk nonmetastatic uveal melanoma were collected on the occasion of primary treatment or follow-up visit. mRNA expression of tyrosinase and MelanA/MART1 were analyzed by real-time RT-PCR and compared with clinical data at presentation and follow-up by univariate and multivariate analyses.

RESULTS

The RT-PCR assay yielded a positive result in 11 of 110 patients, with five positive findings for tyrosinase and five for MelanA/MART1, and one sample positive for both markers. At a median follow-up of 22 months, 25% of patients had developed metastases and 15% had died. Univariate statistical analysis revealed RT-PCR and the largest tumor diameter as important prognostic factors for the development of metastases and for survival. In a Cox proportional hazard model, RT-PCR result and largest tumor diameter predicted metastases (hazard ratios 7.3 and 2.6, respectively), whereas PCR result, largest tumor diameter, and Karnofsky performance status were significant variables for disease-specific survival (hazard ratios 22.6, 4.7, and 6.0, respectively). Analysis of individual RT-PCR results revealed both tyrosinase and MelanA/MART1 transcripts as independent prognostic factors.

CONCLUSION

The presence of tyrosinase or MelanA/MART1 transcripts is an independent prognostic factor in patients with high-risk primary uveal melanoma for subsequent development of metastases and for survival and can be used to select patients for adjuvant treatment studies.

Prognostic role of circulating melanoma cells detected by reverse transcriptase-polymerase chain reaction for tyrosinase mRNA in patients with melanoma

A need for factors predictive of prognosis is present in patients who are diagnosed with malignant melanoma. The detection of circulating melanoma cells by reverse transcriptase-polymerase chain reaction for tyrosinase mRNA is a possible negative prognostic factor. The aim of this study was to assess the prognostic value of reverse transcriptase-PCR for tyrosinase mRNA in peripheral blood samples. From January 2000 to February 2003, duplicate blood samples were drawn from 114 melanoma patients following surgery and informed consent, and were tested with reverse transcriptase-PCR, for tyrosinase mRNA. Outer primers for the first PCR were R1 (sense): TTGGCAGATTGTCTGTAGCC and R2 (antisense): AGGCATTGTGCATGCTGCT. For the second round of PCR, nested primers were R3 (sense): GTCTTTATGCAATGGAACGC and R4 (antisense): GCTATCCCAGTAAGTGGACT. Threshold for detection of the technique was determined by adding serially diluted MelJuSo cells to healthy volunteer blood samples. Overall, 91 (79.1%) patients tested negative for tyrosinase mRNA and 24 (20.9%) tested positive. The number of patients who tested positive by stage was 3/38 (7.9%) for stage I, 3/22 (13.6%) for stage II, 5/30 (16.7%) for stage III and 13/24 (54.2%) for stage IV (P< 0.0001). 11/90 (12.2%) patients with no evidence of disease (stage I, II and III) tested positive and 13/24 (54.2%) patients with clinically confirmed distant metastases (stage IV) tested positive (P<0.00001). With median follow-up of 372 days or to death (range: 0-1303 days), median progression-free survival has not been reached for tyrosinase-negative patients and was 265 days for tyrosinase-positive patients (P<0.00001, log-rank test=21.07). Median overall survival was 344 days for tyrosinase-positive patients and has not been reached for tyrosinase-negative patients (P=0.0001, log-rank test=21.38). Stage, Breslow thickness and result of RT-PCR were significant prognostic factors for disease-free survival in a multivariate analysis, and stage was the only significant prognostic factor for overall survival. In conclusion, detection of circulating melanoma cells by reverse transcriptase-PCR for tyrosinase mRNA is a significant adverse prognostic factor for disease-free survival in patients with malignant melanoma.

Molecular markers of circulating melanoma cells

Of all skin cancers, cutaneous malignant melanoma (CMM) is the most aggressive and the life expectancy of patients with lymphatic or systemic metastases is dramatically reduced. Understandably therefore, scientists and clinicians have focused on improving diagnostic and prognostic techniques. Of these, perhaps the most promising are multimarker real-time RT-PCR and microarray for detection of circulating CMM cells in peripheral blood. While the optimal set of markers is still to be identified that can accurately assess disease severity and progression at all clinical stages of the disease, recent progress has been dramatic. Here we provide an exhaustive review of recent studies in which a variety of markers are assessed. Moreover, the efficacy of the markers relative to clinical stage is discussed in light of experimental findings. From these studies, it is apparent that researchers are now much closer to defining a set of markers of circulating cells that can be utilized in routine diagnostic tests.

Prognostic relevance of baseline and sequential peripheral blood tyrosinase expression in 200 consecutive advanced metastatic melanoma patients

The relationship between the disease course and the prognostic relevance of sequential tyrosinase reverse transcription-PCR assay in the peripheral blood of advanced metastatic melanoma patients was ascertained. The clinical usefulness of tyrosinase in stage IV melanoma patients is still debated, owing to the wide range of variability (positive expression from 30 up to 100% of patients) and the possibility of a transient shedding of melanoma cells into the bloodstream. A total of 200 consecutive stage IV metastatic patients treated at our department were included, 149 with active metastatic disease undergoing systemic therapies (group A), and 51 disease free after surgery (group B). For each patient, a baseline sample was obtained within 3 weeks of either the clinical/radiological demonstration of metastatic disease or the surgical treatment; thereafter, tyrosinase determinations were performed at day 1 of each therapy course before chemotherapy administration or at each follow-up visit. Tyrosinase expression was determined using standard reverse transcription-PCR nested techniques. A baseline positive determination was obtained in 72.5% of the patients with active metastatic disease (group A) but not in any of the patients who were disease free after surgery (group B). Therapy administration induced an early clearance of circulating melanoma cells, from 72.5 to 44.9% at the second down to 29.5% at the third determination. Tyrosinase expression before the third cycle was significantly associated with the clinical response: 56/81 (69.1%) patients with a negative tyrosinase determination obtained a response or a stable disease, whereas 29/34 (85.3%) patients with a positive test developed a progressive disease (P<0.001). A clinical response was observed in all the patients who had a negative tyrosinase at the first three determinations, although all patients whose first three determinations were positive developed a progressive disease. Multivariate analysis showed that baseline tyrosinase status carries an independent prognostic value on both overall survival and time to progression; moreover, tyrosinase results during follow-up were entered as time-dependent covariates in a multivariate analysis and were shown to be the most significant prognostic parameter associated to both overall survival and time to progression. In particular, the presence of a constant positive expression during follow-up was associated with the development of new metastatic sites in 95.6% of patients with active metastatic disease. Our results demonstrate that the discrepancies in the positive tyrosinase rates reported in the literature are related to the disease status at the time of sampling and to chemotherapy administration. Tyrosinase expression in the peripheral blood both at baseline and during follow-up can be considered a reliable prognostic parameter associated with the response to treatment, development of new metastatic sites, time to progression and survival.

Serial detection of circulating tumour cells by reverse transcriptase-polymerase chain reaction assays is a marker for poor outcome in patients with malignant melanoma

Background

Detection of circulating malignant cells (CMCs) through a reverse transcriptase-polymerase chain reaction (RT-PCR) assay seems to be a demonstration of systemic disease. We here evaluated the prognostic role of RT-PCR assays in serially-taken peripheral blood samples from patients with malignant melanoma (MM).

Methods

One hundred forty-nine melanoma patients with disease stage ranging from I to III were consecutively collected in 1997. A multi-marker RT-PCR assay was used on peripheral blood samples obtained at time of diagnosis and every 6 months during the first two years of follow-up (total: 5 samples). Univariate and multivariate analyses were performed after 83 months of median follow-up.

Results

Detection of at least one circulating mRNA marker was considered a signal of the presence of CMC (referred to as PCR-positive assay). A significant correlation was found between the rate of recurrences and the increasing number of PCR-positive assays (P = 0.007). Presence of CMC in a high number (≥2) of analysed blood samples was significantly correlated with a poor clinical outcome (disease-free survival: P = 0.019; overall survival: P = 0.034). Multivariate analysis revealed that presence of a PCR-positive status does play a role as independent prognostic factors for overall survival in melanoma patients, adding precision to the predictive power of the disease stage.

Conclusion

Our findings indicated that serial RT-PCR assay may identify a high risk subset of melanoma patients with occult cancer cells constantly detected in blood circulation. Prolonged presence of CMCs seems to act as a surrogate marker of disease progression or a sign of more aggressive disease.

The prognostic value of circulating tumor cells in patients with melanoma: a systematic review and meta-analysis

BACKGROUND

The detection of circulating tumor cells (CTC) in patients with melanoma represents an appealing prognostic tool, but no consensus exists on this topic. We aimed to comprehensively and quantitatively summarize the evidence for the use of CTC to predict patients' clinical outcome.

METHODS

Fifty-three studies enrolling 5,433 patients were reviewed. Correlation of CTC status with tumor-node-metastasis disease stage and patients' overall (OS) and progression-free (PFS) survival was assessed by means of association statistics and meta-analysis, respectively.

RESULTS

CTC status correlated with both tumor-node-metastasis stage (stage I, 32%; stage II, 41.7%; stage III, 41.1%; stage IV, 47.4%; P(trend) < 0.0001) and survival (OS: hazard ratio, 2.42; 95% confidence interval, 1.7-3.45, P < 0.0001; PFS: hazard ratio, 2.45; 95% confidence interval, 1.78-3.38; P < 0.0001). However, statistical heterogeneity was significant for both OS and PFS, likely underscoring the wide variability in study design. Furthermore, CTC positivity rates in early stages were higher and in the metastatic setting were lower than expected, which indicates an unsatisfactory accuracy of currently available CTC detection assays.

CONCLUSIONS

Our findings suggest that CTC might have a clinically valuable prognostic power in patients with melanoma. However, the heterogeneity of the studies thus far published warrants caution not to overestimate the favorable results of pooled data.

Serum Protein S-100 Predicts Clinical Outcome in Patients with Melanoma Treated with Adjuvant Interferon – Comparison with Tyrosinase RT-PCR

OBJECTIVE

To study the clinical value of the determination of serum S-100 protein as a single tumor marker or in combination with tyrosinase RT-PCR in patients with melanoma receiving adjuvant interferon.

PATIENTS AND METHODS

Patients were tested for serum S-100 protein luminoimmunometric assay and for blood tyrosinase mRNA (RT-PCR), before starting interferon and every 2-3 months thereafter.

RESULTS

One hundred and six patients (stage IIA, 27; IIB, 19; III, 49; and IV, 11) were included in the study. Median follow-up was 51 months (range 2-76). In the univariate analysis, under treatment S-100 > or =0.15 microg/l and a positive RT-PCR correlated with a lower disease-free survival and overall survival (OS). In the multivariate analysis, clinical stage, under therapy positive RT-PCR and S-100 levels > or =0.15 mug/ml, were independent prognostic factors for OS. The hazard ratio for OS was 3.9 (95% CI, 1.67-9.15; p = 0.004) and 2.2 (95% CI, 1.05-4.6; p = 0.016) for S-100 > or =0.15 microg/l and positive RT-PCR, respectively. When both techniques where combined, a positive RT-PCR indicated a poorer clinical outcome only in patients with S-100 <0.15 microg/l.

CONCLUSIONS

S-100 > or =0.15 microg/l and a positive RT-PCR during adjuvant interferon therapy indicate a high risk of death in resected melanoma patients. S-100 determination has a higher positive predictive value than RT-PCR, while tyrosinase RT-PCR adds prognostic information in patients with S-100 <0.15 microg/l.

Molecular Staging in Stage II and III Melanoma Patients and Its Effect on Long-Term Survival

Purpose

To assess the prognostic value of serial reverse transcriptase polymerase chain reaction (RT-PCR) -based measurements of tyrosinase mRNA in peripheral blood of stage II and III melanoma patients.

Patients and Methods

During routine follow-up of American Joint Committee on Cancer stage II and III melanoma patients, serial testing for tyrosinase transcripts in peripheral blood was performed by RT-PCR. The PCR results were compared with the clinical data collected during the follow-up.

Results

Over a period of 3 years, 111 patients (78 stage II and 33 stage III patients) were enrolled, and tyrosinase determinations were carried out. The 6-year disease-specific survival probability was 97% for patients always showing negative RT-PCR results and 67% for patients who tested positive at least once. In a Cox proportional hazards model, the prognostic value of sex, age, site of primary tumor, histologic subtype, stage, Breslow's tumor thickness, Clark level, and the time-dependent variable PCR result was assessed. Patients with a positive RT-PCR test had a distinctly higher risk of dying from melanoma, with a hazard ratio of 12.6 (95% CI, 3.4 to 46.3; P < .001).

Conclusion

Our study shows a strong association between PCR and disease-specific survival time. Detection of tyrosinase mRNA in peripheral blood may be of similar importance for the clinical course of melanoma as the detection of micrometastatic disease in the sentinel lymph node. Whether a combination of these two factors leads to a better definition of the prognosis of melanoma patients is under investigation in current studies.

RT-PCR tyrosinase expression in the peripheral blood of melanoma patients

Controversial data are reported in the literature concerning the role of peripheral blood tyrosinase messenger RNA reverse transcription PCR analysis in melanoma patient management. Some papers assess the clinical relationship between tyrosinase expression and disease outcome, while others address the high degree of variability in the positive rate percentage and demonstrate the transient shedding of melanoma cells in the bloodstream. An overview of the current knowledge about the applications and limitations of tyrosinase analysis compared with other biologic markers is presented herein. Tyrosinase expression should not be considered as a tumor burden-related marker in the peripheral blood, but rather as a measure of the potential increased risk of metastatic spreading. In this view, reverse transcription PCR gains a clinical significance when sequential determinations are performed during follow-up, whereas the evaluation of a single sample, either positive or negative, does not bring any additional clinical information.

Detection of melanoma cells in the lymphatic drainage after lymph node dissection in melanoma patients by using two-marker reverse transcriptase-polymerase chain reaction assay

BACKGROUND

The aim of this study was to evaluate the role of melanoma gene expression as a marker of the presence of melanoma cells in lymphatic drainage routinely collected after lymphadenectomy and to correlate reverse transcriptase-polymerase chain reaction (RT-PCR) assay results with recurrence, survival, and prognostic factors.

METHODS

We collected 24-hour postoperative lymphatic drainage samples (between days 2 and 4) from 93 patients with stage III melanoma who underwent radical lymphadenectomy between May 2002 and November 2003. We used RT-PCR assays with primers specific for the tyrosinase and MART-1 (Melan-A) genes. The samples were considered positive if at least one marker was expressed. Median follow-up time was 12.8 months.

RESULTS

In 18 (19.4%) of 93 patients, the RT-PCR assay results were positive: in 8 of 18 for tyrosinase only, in 7 of 18 for MART-1 only, and in 3 of 18 for both markers. We observed a significantly higher recurrence rate in patients with positive RT-PCR results (15 of 18; 83%) than negative results (26 of 75; 35%; P = .0001). Positive results of RT-PCR correlated with the number of involved lymph nodes (P = .0001) and extracapsular extension of nodal metastases (P = .03). We observed significant differences in overall and disease-free survival for RT-PCR-positive and -negative patients in univariate and multivariate analyses.

CONCLUSIONS

We observed positive RT-PCR assay results for melanoma cells in the lymphatic drainages of approximately 20% of patients after lymphadenectomy. This correlated significantly with early recurrence and shorter survival. These results may suggest that the RT-PCR assay could be useful for routinely analyzing postoperatively collected lymphatic drainage in stage III melanoma patients and for predicting disease progression.

The history and future of melanoma staging

The evolution and progressive refinement of an internationally accepted melanoma staging system over the last 50 years has resulted in much greater accuracy and increased utility, but the staging process has become more complex and less intuitive. This raises the question of whether melanoma staging should continue to develop with ever-increasing levels of complexity, or whether attempts should be made to produce an alternative system that is simpler and more intuitive. The current, TNM-based American Joint Committee on Cancer (AJCC) staging system for melanoma incorporates only some of the prognostic factors of proven significance. However, the information that is now available about these and other, well-documented prognostic factors allows accurate prediction of an individual melanoma patient's prognosis using a computer-generated estimate. Thus an alternative staging strategy that could be considered in the future would be to use such an estimate to obtain a numerical score for each patient, based on all available information agreed to be of prognostic relevance. A stage grouping could then be assigned on the basis of that score, according to previously determined score ranges for each stage and substage. The advantages of such a system would be that it would allow more reliable comparison of treatment results within and between institutions, and would provide more equivalent stratification groups for patients entering clinical trials of new therapies and those entering adjuvant therapy trials. A further advantage would be that because there would be a direct link between staging and prognostic estimate, such a system would be more readily able to be understood in an intuitive fashion.

Detection of tyrosinase and tyrosinase-related protein 1 sequences from peripheral blood of melanoma patients using reverse transcription-polymerase chain reaction

BACKGROUND

malignant melanoma has one of the highest rates of metastasis. Unlike other solid cancers, no sensitive tumor markers or laboratory tests that can provide information of the risk of metastasis and predict the prognosis have yet been established.

OBJECTIVE

the study was done to establish a RT-PCR sensitive and specific enough to detect melanocyte-specific transcripts from peripheral blood cells.

METHODS

peripheral white blood cells were collected from 30 healthy donors and 43 melanoma patients. Melanocyte-specific tyrosinase (TYR) and tyrosinase-related protein 1 (TYRP1) were selected as targets of RT-PCR. The sensitivity of detection using SK-mel-23 melanoma cells and rates of false-positiveness using non-melanoma blood were compared between single-step PCR and nested PCR. Analysis of melanoma blood samples was carried out by the single-step PCR.

RESULTS

the nested RT-PCR amplified the TYR and TYRP1 sequences from 14 and 2 of the 30 healthy bloods, respectively. However, the single-step RT-PCR did not amplify TYR or TYRP1 sequences from any of the healthy controls. Our single-step RT-PCR detected 1.7 and 0.8 SK-mel-23 melanoma cells per ml blood for TYR and TYRP1, respectively. Overall, TYR mRNA was detected in 15 of the 43 melanoma patients (34.9%), and TYRP1 mRNA in 16 of the 43 (37.2%). The specificities of detection of TYR and TYRP1 were 83.3 and 88.9%, respectively.

CONCLUSION

our single-step RT-PCR for TYR and TYRP1 mRNAs is more specific than the previous nested RT-PCR for TYR and applicable to detect circulating melanoma cells.

Tyrosinase expression in the peripheral blood of stage III melanoma patients is associated with a poor prognosis: a clinical follow-up study of 110 patients

The aim of this study is to define the relationship between the tyrosinase expression in the peripheral blood and the clinical course of the disease in stage III disease-free melanoma patients after radical lymph node dissection. RT-PCR techniques were used to identify tyrosinase mRNA in 110 patients; a total of 542 blood samples were investigated. In all, 54 patients (49%) showed at least one positive result; 13 patients (11.8%) showed baseline positive results: six became negative thereafter, whereas seven showed follow-up positive results until disease progression occurred. One or more positive determinations were found during follow-up in 41 patients with negative baseline tyrosinase. No correlation was found between baseline results and the relapse rate or disease-free survival (DFS), whereas a significant correlation was found between positive tyrosinase results and disease recurrence during follow-up. In fact, 72.9% of positive patients relapsed, but only 19.3% of negative cases did so. The median interval between the positive results and the clinical demonstration of the relapse was 1.9 months (range 1-6.6). Disease-free survival multivariate analysis selected, as independent variables, Breslow thickness (P=0.05), lymph node involvement according to the AJCC classification (P=0.05) and tyrosinase expression (P=0.0001). In conclusion, RT-PCR tyrosinase mRNA expression is a reliable and reproducible marker associated with a high risk of melanoma progression and we encourage its clinical use in routine follow-up.

Prognostic value of multiple reverse transcription-PCR tyrosinase testing for circulating neoplastic cells in malignant melanoma

BACKGROUND

The reverse transcription-PCR tyrosinase assay (TYR test) cannot reliably detect malignant melanoma (MM) cells in blood as the cells often circulate at low concentrations. We evaluated the prognostic value of multiple TYR testing, the prognostic significance of individual positive TYR test results (TYR+) in asymptomatic melanoma patients, and whether statistical analysis could help in the interpretation of results of a test that measures phenomena that typically occur below its detection threshold.

METHODS

MM patients in stages I-IV (n = 150) underwent multiple testing with the TYR test during the course of their disease. TYR testing was performed as described by Smith et al. (Lancet 1991;38:1227-9). Statistical analyses were performed with the logistic function and t-test procedures.

RESULTS

The relationship between MM stage and the frequency of TYR+ was statistically significant (P = 0.011). Higher frequency of TYR+ in clinically asymptomatic patients after complete resection of the primary tumor was associated with an increased risk of recurrence of MM (prognostic sensitivity, 62%; specificity, 78%).

CONCLUSIONS

A single positive TYR test provides a warning for disease relapse, suggesting that multiple TYR testing might provide more reliable predictions of disease progression. Multiple testing and statistical analysis using a logistic function might allow for the interpretation of apparently inconsistent results of tests for very rare cells.

Detection of disseminated tumour cells in blood and bone marrow samples of patients undergoing hepatic resection for metastasis of colorectal cancer

BACKGROUND

In 50-60 per cent of patients who undergo hepatic resection for metastasis of colorectal cancer the first site of tumour recurrence is extrahepatic, indicating the presence of more extensive disease at the time of resection. The aim of this study was to evaluate whether the presence of disseminated tumour cells in blood and bone marrow could predict extrahepatic tumour recurrence.

METHODS

Cytokeratin 20 (CK20) reverse transcriptase-polymerase chain reaction was used to study the presence of tumour cells in preoperative peripheral blood and bone marrow samples from 41 patients with liver metastasis scheduled for surgical resection.

RESULTS

CK20 expression was detected in six of 41 peripheral blood samples and in eight of 32 bone marrow samples. There was no correlation between CK20-positive samples and subsequent extrahepatic recurrence. Positive blood samples did, however, correlate with high serum carcinoembryonic antigen level and large tumour volume. None of the 14 patients previously treated with chemotherapy had CK20-positive samples, whereas six of 27 blood and eight of 20 bone marrow samples were positive in the chemotherapy-naive group.

CONCLUSION

Although the number of patients in this study is limited, the presence of disseminated tumour cells did not predict subsequent extrahepatic recurrence. The results strongly suggest that the presence of circulating tumour cells in peripheral blood may reflect transient shedding of tumour cells related to large tumour volume.

The role of molecular staging in malignant melanoma

AIMS

To review the role of tyrosinase RT-PCR in the detection of clinically occult metastatic disease, both within the regional lymph nodes and peripheral blood of patients with malignant melanoma. Secondly, to assess whether the detection of such minimal disease has clinical implications for patients with melanoma.

METHODS

A review of the literature was undertaken by searching the MEDLINE database for the period 1966-2002 without any language restrictions. Keywords included 'Molecular staging of melanoma', 'Reverse transcription polymerase chain reaction', 'Malignant melanoma' and 'Tyrosinase'.

CONCLUSIONS

Detection of tyrosinase RT-PCR positive cells within the peripheral blood correlates with the clinical stage of malignant melanoma, the primary tumour thickness and other known prognostic indicators. Positive tyrosinase RT-PCR is associated with a reduction of disease-free survival and overall survival. Current studies demonstrate a higher rate of recurrence in RT-PCR positive patients with clinical stage II and III disease. Implications of a positive result within the regional lymph nodes are less well defined. A significant correlation has been demonstrated between positive results and increasing primary melanoma thickness. However, a large number of false-positive results have been demonstrated, due to benign naevi and schwann cells, which may hamper any statistically significant conclusions being reached.

Diagnostic value and prognostic significance of protein S-100beta, melanoma-inhibitory activity, and tyrosinase/MART-1 reverse transcription-polymerase chain reaction in the follow-up of high-risk melanoma patients

BACKGROUND

Cutaneous melanoma is the most aggressive form of skin carcinoma in humans, frequently with a rapid progression of disease. To detect early developing metastasis, laboratory tests to determine levels of lactate dehydrogenase (LDH) and alkaline phosphatase (AP) form part of the regular follow-up, but often cannot discover recurrent disease at a sufficiently early stage.

METHODS

To evaluate the diagnostic accuracy of protein S-100beta (S-100beta), melanoma-inhibitory activity (MIA), LDH, AP, and tyrosinase/MART-1 reverse transcription-polymerase chain reaction (RT-PCR), the authors included 296 consecutive AJCC Stage II or III clinically disease-free melanoma patients. Follow-up examinations were performed every 3 months and blood samples were drawn to determine the levels of these tumor markers.

RESULTS

Metastasis occurred in 41 of the 296 patients during a median follow-up period of 19 months (range, 1-33 months). The sensitivity to detect new metastases was 29% for protein S-100beta, 22% for MIA, 2% for LDH, 17% for AP, and 24% for RT-PCR. The diagnostic accuracy was best for MIA (86%) and S-100beta (84%), whereas AP (79%), LDH (77%), and RT-PCR (72%) demonstrated lower values. Elevated values of S-100beta and MIA during follow-up examinations were associated with decreased survival rates in the further course of the disease, but pathologic findings of the other tumor markers showed no prognostic impact.

CONCLUSIONS

To the authors' knowledge, the current study is the first comparison of the diagnostic accuracy of currently available tumor markers in the follow-up of high-risk melanoma patients. Protein S-100beta and MIA demonstrated a higher sensitivity, specificity, and diagnostic accuracy in the diagnosis of newly occurring metastasis compared with to the tumor markers AP, LDH, and RT-PCR diagnostics. Therefore, the tumor markers S-100beta and MIA may be useful in the follow-up of disease-free Stage II and III melanoma patients.

Detection of circulating melanoma cells by a two-marker polymerase chain reaction assay in relation to therapy

Malignant melanoma is one of the most rapidly increasing cancer types, and patients with metastatic disease have a very poor prognosis. Detection of metastatic melanoma cells in circulation may aid the clinician in assessing tumor progression, metastatic potential, and response to therapy. Tyrosinase is a key enzyme in melanin biosynthesis. The gene is actively expressed in melanocytes and melanoma cells. Melan A is a differentiation antigen that is expressed in melanocytes. The presence of these molecules in blood is considered a marker for circulating melanoma cells. In this study, we analyzed the usefulness of this marker combination in evaluating the response to therapy in the blood of 30 patients with malignant melanoma. Circulating cells were detected by a reverse-transcriptase-polymerase-chain reaction. The tyrosinase expression was observed in 9 (30%) patients and Melan A in 19 (63.3%) patients before therapy. Following treatment, the tyrosinase mRNA was detected in only one patient, while Melan A transcripts were still present in 14 patients. We suggest that this molecular assay can identify circulating melanoma cells that express melanoma-associated antigens and may provide an early indication of therapy effectiveness.

Prognostic value of circulating melanoma cells detected by reverse transcriptase-polymerase chain reaction

PURPOSE

Factors that are predictive of prognosis in patients who are diagnosed with malignant melanoma (MM) are widely awaited. Detection of circulating melanoma cells (CMCs) by reverse transcriptase-polymerase chain reaction (RT-PCR) has recently been postulated as a possible negative prognostic factor. Two main questions were addressed: first, whether the presence of CMCs, defined as the patient being positive for any of the three markers, had a prognostic role; and second, what the predictive value of each individual marker was.

PATIENTS AND METHODS

A consecutive series of 200 melanoma patients observed between January 1997 and December 1997, with stage of disease ranging from I to IV, was analyzed by semiquantitative RT-PCR. Tyrosinase, p97, and MelanA/MART1 were used as markers to CMCs on baseline peripheral blood samples. Progression-free survival (PFS) was used as a unique end point and was described by the product limit method. Multivariable analysis was applied to verify whether the auspicated prognostic value of these markers was independent of the stage of disease, and a subgroup analysis was performed that excluded patients with stage IV disease.

RESULTS

Overall, 32% (64 of 200) of patients progressed, and a median PFS of 52 months in the whole series was observed. The presence of CMCs and the markers individually or combined was predictive of prognosis in the univariate analysis but did not provide additional prognostic information to the stage of disease in multivariable models. In the subgroup analysis of stage (ie, I-III subgroup), similar results were observed.

CONCLUSION

Detection of CMCs in peripheral blood samples at the time of MM diagnosis by semiquantitative RT-PCR does not add any significant predictive value to the stage of disease. Thus, this approach should not be used in clinical practice, and further studies are required to determine its usefulness.

Tyrosinase mRNA in blood of patients with melanoma treated with adjuvant interferon

PURPOSE

To evaluate the clinical significance of the detection of circulating melanoma cells in patients treated with adjuvant interferon and to determine their potential value as a marker of interferon response.

PATIENTS AND METHODS

We prospectively analyzed 616 peripheral-blood samples from 120 melanoma patients with stage IIA (n = 33), IIB (n = 22), III (n = 50), or IV (surgically resected) (n = 15) disease receiving adjuvant interferon alfa-2b therapy. Tyrosinase mRNA was assayed by reverse transcriptase polymerase chain reaction (RT-PCR) as a marker of circulating melanoma cells before the start of interferon and every 2 to 3 months thereafter.

RESULTS

With a median follow-up time of 32.3 months (range, 7.1 to 77.5 months), 47 patients (39.8%) relapsed and 31 (26%) died. During adjuvant interferon treatment, 76 patients (64%) had undetected circulating melanoma cells and 44 patients (36%) had a positive RT-PCR result in at least one sample. Actuarial 5-year disease-free survival was 62% in patients with persistently negative RT-PCR during interferon treatment and 38% for patients with positive RT-PCR during interferon (P =.02). Actuarial 5-year overall survival was 75% and 50%, respectively (P =.03).

CONCLUSION

Patients with melanoma and tyrosinase mRNA detected in the blood during adjuvant interferon therapy had a worse prognosis compared with patients with undetected tyrosinase mRNA during treatment. Further investigation into the detection of circulating melanoma cells as a surrogate marker of response to adjuvant interferon therapy is warranted.

Magnetic bead RT-PCR: establishment of a new method for detecting circulating melanoma cells

This study was performed to detect circulating melanoma cells in peripheral blood using a novel method based on magnetic-activated cell separation (MACS) followed by a nested reverse transcriptase-polymerase chain reaction (RT-PCR) for tyrosinase and MART-1 mRNA. Samples to be tested were enriched for tumour cells either by isolating melanoma cells using two anti-melanoma antibodies (MART-1 and HMB-45) or by CD45 depletion of the non-melanoma cell fraction. The tumour cell-enriched fractions were subjected to mRNA isolation using oligo-deoxythymidylate (oligo-dT) magnetic beads followed by a nested RT-PCR. Sensitivity was assessed by spiking experiments and compared with a commonly used total RNA isolation system previously established in our department. Positive isolation of melanoma cells showed insufficient sensitivity, whereas negative isolation by depletion of leukocytes showed a detection limit of at least one melanoma cell per millilitre of whole blood. In further experiments, the depletion assay was applied to 25 peripheral blood samples of melanoma patients. The preliminary data obtained from the new method indicate a comparable detection rate to the established total RNA extraction method. However, not all the results were concordant. Therefore, future experiments need to be performed with a statistically greater number of patients.

Pathologic staging of melanoma

The American Joint Committee on Cancer (AJCC) recently launched a new staging system for cutaneous melanoma that was based on clinical experience with a large number of patients treated in major centers worldwide. As this system includes various histopathologic parameters of the primary melanoma and of melanoma metastasis, including micrometastases in the sentinel lymph node (SLN), they are discussed here. Special attention is given to ulceration of the primary tumor, because it remains a dominant prognostic parameter in addition to tumor thickness. Molecular markers that may reflect aggressive behavior of the primary melanoma also are described. Finally, pathologic examination of SLNs is addressed with emphasis on the efficacy of various microstaging approaches.

Prognostic significance of the sequential detection of circulating melanoma cells by RT-PCR in high-risk melanoma patients receiving adjuvant interferon

The purpose of this study was to address the prognostic significance of circulating melanoma cells by reverse transcriptase-polymerase chain reaction in the peripheral blood of stage IIB and III melanoma patients on high-dose adjuvant interferon at multiple sequential time points from initiation of treatment. Tyrosinase mRNA in peripheral blood from these patients was assayed by reverse transcriptase polymerase chain reaction prior to initiation of adjuvant interferon, at completion of 1 month of intravenous interferon and at 3 monthly intervals until progression. Four hundred and eighteen blood samples from 60 melanoma patients were analysed. The median follow-up time calculated from the time of inclusion in the study was 23 months (range 2-38 months). Tyrosinase mRNA in blood was detected in 42 (70%) of 60 patients: 16 (76%) of 21 stage IIB patients and 26 (66% ) of 39 stage III patients. The presence of tyrosinase mRNA in blood was correlated with a shorter disease-free survival (P : 0.03) and in multivariante analysis was an independent prognostic factor for relapse. Patients who seroconverted to a negative reverse-transcriptase-polymerase chain reaction after induction treatment had a significantly lower probability of recurrence. The presence of circulating melanoma cells is a marker of a high relapse risk and shorter disease-free survival whether detected postoperatively or during follow-up. Tyrosinase mRNA amplification by reverse-transcriptase-polymerase chain reaction may be a useful tool for monitoring the efficacy of adjuvant treatment in stage IIB and III melanoma patients.

Limitations of cytokeratin 20 RT-PCR to detect disseminated tumour cells in blood and bone marrow of patients with colorectal cancer: expression in controls and downregulation in tumour tissue

AIMS

Despite informative staging of patients with colorectal cancer, some patients with localised disease at diagnosis will develop recurrence or metastasis. Attempts to improve staging include sensitive detection of disseminated tumour cells in blood and bone marrow by reverse transcriptase polymerase chain reaction (RT-PCR). The results of this study have been considered in relation to the controversial results in the literature to elucidate the usefulness of cytokeratin 20 (CK20) RT-PCR to detect disseminated tumour cells further.

PATIENTS/METHODS

Blood and bone marrow samples from 30 patients with colorectal cancer were studied by CK20 RT-PCR. Specificity was evaluated in 47 blood and 15 bone marrow samples from non-cancer controls. In addition, the expression of CK20 mRNA and protein was studied in normal and tumour colon tissue samples.

RESULTS

CK20 expression was detected in nine of 30 and nine of 19 of the blood and bone marrow samples from patients with colorectal cancer, respectively. In non-cancer control blood and bone marrow samples, CK20 expression was detected in 10 of 47 and four of 15, respectively. A difference between patient and control samples may be observed in terms of frequency of positive PCR tests. In tissue samples, CK20 mRNA expression was downregulated in tumour compared with normal colon tissue.

CONCLUSIONS

CK20 expression was downregulated in tumour tissue compared with normal colon and a background expression of CK20 was seen in some control blood and bone marrow samples. Despite a lack of standardisation (which hampers comparison of studies), these results, together with other reports in the literature, suggest that CK20 may still be a suitable marker, but that background expression and threshold setting should be studied further.

Reverse transcriptase-polymerase chain reaction detection of circulating tumor cells in patients with melanoma: correlation with clinical stage, tumor thickness and histological type

The aim of this study was to evaluate the correlation between the detection of circulating melanoma cells and prognostic criteria for malignant melanoma such as clinical stage, tumor thickness and histological type of the primary tumor. Using a reverse transcriptase-polymerase chain reaction (RT-PCR) technique, melanoma cells were identified by detecting tyrosinase mRNA in peripheral blood from 58 patients with malignant melanoma classified according to the American Joint Committee on Cancer guidelines. The results of the RT-PCR assay for tyrosinase were related to two prognostic markers typically used to evaluate these tumors: clinical stage and thickness. Positive PCR results were more frequent in primary tumors measuring > 4 mm (83%) than in thinner tumors (1.1-4.0 mm, 74%; < or = 1.0 mm, 23%) (P = 0.005). No statistical correlation was found between the PCR results and histological appearance of the primary tumor. Although further studies are necessary, our results suggest the possible application of the PCR assay for tyrosinase mRNA in clinical evaluation of the prognosis of malignant melanoma.

Quantitative nested real-time RT-PCR specific for tyrosinase transcripts to quantitate minimal residual disease

BACKGROUND

Quantification of tumor markers expressed by occult-circulating tumor cells may be of prognostic value in a variety of neoplasms and disease stages. Here, we report on a quantitative nested real-time polymerase chain reaction (PCR) assay to quantify rare transcripts using the Light Cycler system. Tyrosinase mRNA, only expressed by melanocytes and melanoma cells, was used as the model tumor marker.

METHODS

For the establishment and sensitivity testing of this novel real-time PCR assay, 10 ml EDTA blood from healthy volunteers was spiked with 10(1)-10(5) MKR cells (the melanoma cell line). Following RNA extraction and cDNA synthesis, nested and single round PCRs were performed. Subsequently, 35 blood samples of 22 melanoma patients were analyzed.

RESULTS

Nested PCRs provided quantitative data with a quantitative range of five orders of magnitude of tyrosinase mRNA equivalent to 1-10(4) MKR cells/ml of blood. Nested PCR with 35 pre-amplification cycles displayed the quantitative data for nine tyrosinase transcript-positive samples out of 35 blood samples, whereas nested PCR with 20 pre-amplification cycles or single round PCR were less sensitive.

CONCLUSIONS

These experiments indicate that nested PCR, which is much more sensitive than single round PCR, is a useful tool even for the quantification of rare transcripts-a result with important implications for the study of minimal residual disease (MRD) in melanoma as well as in other malignancies.

Molecular pathology of tumor metastasis. II. Molecular staging and differential diagnosis

Molecular Pathology of Tumor Metastasis With the development of non-invasive methods, diagnosis of metastasis from various solid malignancies has become a routine task for diagnostic pathology. However, the differential diagnosis between primary and metastatic cancers and the precise identification of various metastatic cancer types requires the coordinated use of various morphological (light- and electron microscopic-), immunological and molecular techniques. The detection of the lymphatic spread of the primary tumor may now based on the sentinel lymph node technology while the identification of the hematogenous progression may be based on the analysis of the peripheral blood and the bone marrow. More and more frequently these techniques employ highly sensitive immunological and molecular techniques. Accordingly, clinical staging is now confronted with the results of molecular staging, where the only techniques which are able to detect cancer cells are immunocytochemistry or nucleic acid-based methodology. Although several clinical studies have provided evidences for the impact of the immunocytochemistry-based identification of micrometastases on the survival of patients with various type of cancers, none of these methods have become part of standard diagnostic protocols. Although more sensitive molecular techniques are being introduced to identify micrometastasis, their clinical significance is yet unknown. Multicentric clinical trials are now warranted to establish the clinical impact of molecular staging in various cancer types. Without the integration of these methods into the prognostic/predictive pathological protocols it is difficult to envision significant improvement in the results of cancer therapy.

Detection of tumor cells in the portal and peripheral blood of patients with colorectal carcinoma using competitive reverse transcriptase-polymerase chain reaction

BACKGROUND

In spite of many reports, it remains unclear whether the presence of tumor cells in circulating blood flow predicts a poor prognosis.

METHODS

Competitive seminested reverse transcriptase-polymerase chain reaction (RT-PCR), a technique for the quantitative detection of tumor cells, was applied to detect the presence of tumor cells in portal and peripheral blood samples from 121 patients with colorectal carcinoma and to clarify their clinical significance. This technique can detect one carcinoembryonic antigen (CEA) mRNA-expressing tumor cell in 1 x 10(5) normal lymphocytes.

RESULTS

Six of 33 healthy volunteers (18%) demonstrated a positive reaction to this technique. CEA mRNA expression was detected in the portal blood in 51% of patients and in the peripheral blood in 42% of patients. The results from the two blood samples were consistent in 91% of patients. The positive expression rates for portal blood in patients with T1 tumors and those with TNM Stage I disease were 38% and 45%, respectively. The positive rate was significantly higher in patients with colon carcinoma and those with Stage III or IV disease. CEA mRNA expression, quantitatively measured (x 10(-8)/beta-actin), was 22.9 +/- 35.1 in the portal blood and 19.9 +/- 40.0 in the peripheral blood, with no statistically significant difference. A significant positive correlation was noted between portal and peripheral CEA mRNA expression levels according to Spearman correlation analysis (correlation coefficient = 0.78; P < 0.01). Multivariate analysis revealed that the positive rate and level of CEA mRNA expression in the portal and peripheral blood did not appear to be influenced by the established prognostic factors.

CONCLUSIONS

The presence of circulating tumor cells might be of less value as a prognostic factor because they also can be detected in patients with early-stage colorectal carcinoma and appeared to be independent of the conventional prognostic factors.

Detection of melanoma cells in sentinel lymph nodes, bone marrow and peripheral blood by a reverse transcription-polymerase chain reaction assay in patients with primary cutaneous melanoma: association with Breslow's tumour thickness

BACKGROUND

Tyrosinase reverse transcription-polymerase chain reaction (RT-PCR) has been shown to be highly sensitive in detecting tumour cells in melanoma patients.

OBJECTIVE

To assess whether the detection of minimal residual disease by RT-PCR is improved by concomitant analysis of sentinel lymph nodes (SLNs), bone marrow (BM) and peripheral blood (PB) in patients with primary melanoma.

METHODS

Thirty-five SLNs, 41 BM samples and 26 PB specimens from 26 patients with primary cutaneous melanoma (tumour thickness > or = 0.75 mm) were examined by nested RT-PCR for tyrosinase and Melan-A. SLNs and BM samples were also analysed by histopathology. RT-PCR findings were related to tumour thickness of the primary melanoma.

RESULTS

Overall, melanoma cells were detected by RT-PCR in 13 of 26 patients (50%). Seven patients had positive RT-PCR results in their SLNs (27%), including all patients (n = 4) with histologically positive SLNs, two patients had positive findings in their BM exclusively detected by RT-PCR (8%) and six patients in PB (23%). The presence of tumour cells detected by RT-PCR in SLNs was not related to the presence of melanoma cells in BM and/or PB. The incidence of RT-PCR-positive SLNs was significantly associated with greater tumour thickness (P = 0.004). Both patients with positive RT-PCR findings in their BM had a large tumour thickness (> or = 2 mm). No association between positive RT-PCR findings in PB and greater tumour thickness was observed.

CONCLUSIONS

RT-PCR-positive SLNs were strongly associated with greater tumour thickness, underlining the prognostic significance of SLN positivity. Similar to certain epithelial malignancies, molecular investigation of the BM might provide complementary prognostic information in the early stages of melanoma. In contrast, no association between positive RT-PCR results in PB and increasing tumour thickness was found, implying that RT-PCR findings in PB are of doubtful clinical relevance in primary melanoma.

Reliability of PCR-based detection of occult tumour cells: lessons from real-time RT-PCR

For the molecular detection of rare tumour cells in clinical samples, real-time reverse transcription-polymerase chain reaction (RT-PCR) offers two important advantages over conventional RT-PCR assays: the results are quantitative and, perhaps more importantly, it facilitates exact sensitivity controls on a per sample basis as well as exact comparison of different assay protocols. We report here on quantitative results obtained with different protocols for RNA isolation and cDNA synthesis for amplification of beta2-microglobulin transcripts using the light cycler system. Furthermore, housekeeping gene-specific PCRs were compared with PCRs specific for an artificial transcript (internal standard) detected simultaneously at a level comparable to the wild-type sequence. Artificial tyrosinase transcripts derived from a vector construct stably transfected into a human lymphoma cell line were used as a model to test the usefulness of artificial internal standards as an alternative to housekeeping genes. The highest RNA yields were obtained using a combination of phenol-chloroform extraction and the High Pure RNA Isolation Kit. Analysing beta2-microglobulin transcript-specific RT-PCRs, the highest sensitivity was obtained for cDNAs generated with Omniscript reverse transcriptase and oligo-p(dT)15 primer. Regarding patient blood samples, RT-PCRs specific for beta2-microglobulin, porphobilinogen deaminase and artificial tyrosinase transcripts provided quantitative data for all, for 18 out of 21, and for 10 out of 21 samples, respectively. Quantification of beta2-microglobulin transcripts by the light cycler system defined the protocol revealing the highest cDNA quality. Comparisons of quantitative data from RT-PCRs specific for beta2-microglobulin, porphobilinogen deaminase and artificial tyrosinase transcripts enabled us to determine a close range for crossing points within which sufficient cDNA quality can be guaranteed, even for the detection of rare transcripts. PCRs specific for the artificial internal standard are ideally suited for cDNA quality assessment on a per sample basis.

Minimal residual disease in melanoma

A number of specific genes encoding for melanosomal proteins are selectively expressed in melanocytes and melanomas. For detection of circulating melanoma cells, the expression of the tyrosinase gene is most widely used. Several cohorts of melanoma patients from single institutions have been analyzed by various research groups for the presence of circulating melanoma cells in all stages of disease. The percentage of patients with evidence of occult tumor dissemination has been correlated with stage of disease in several, but not all, reports. Two prospective analyses suggest that the PCR result is of prognostic value in melanoma. Several laboratories have found PCR evidence for circulating melanoma cells in the vast majority of untreated patients with stage IV disease, although other groups have reported much lower frequencies. Taken together, there is a wide range of results. Methodological differences likely account for this discrepancy. With the availability of true quantitative RT-PCR systems, such as the Light Cycler system, accurate quantification of tyrosinase transcripts over a range of 1-10,000 tumor cells per ml of blood is possible. Quantitative RT-PCR systems also dramatically improve quality control, since exact quantitation of housekeeping gene mRNA facilitates determination of sample quality.

Facts and pitfalls in the detection of tyrosinase mRNA in the blood of melanoma patients by RT-PCR

Reverse transcription (RT) of tyrosinase mRNA and specific cDNA amplification to facilitate the early detection of circulating tumor cells in melanoma patients have been reported. The significance and practical value of these procedures for the diagnosis of tumor dissemination in melanoma patients is, however, still unclear. We analyzed peripheral blood samples of melanoma patients of different clinical stages for the presence of tyrosinase mRNA by reverse transcriptase polymerase chain reaction (RT-PCR). In addition to a nested RT-PCR-based system, we evaluated the new PCR enzyme-linked immunosorbent assay tyrosinase system for sensitivity and specificity in detecting circulating melanoma cells. Our results showed a high sensitivity and specificity for this system in detecting one melanoma cell in 1 ml of whole blood. Using different methods of detection, no tyrosinase mRNA was detectable in blood samples of patients with primary melanoma and regional lymph node metastases. In a small number of patients with visceral metastases (10-30%), we found tyrosinase mRNA-positive results. Analyses of different blood samples taken at 2-h intervals indicate that tumor cells persist only transiently in the peripheral blood. Successful establishment of melanoma cell growth from tyrosinase mRNA-positive samples indicates that viable tumor cells exist in melanoma patients' peripheral blood. Our results indicate a low amount of tyrosinase-specific transcripts in a small subset of stage IV patients and suggest that the analysis of tyrosinase mRNA in peripheral blood samples is not helpful as a prognostic marker or monitoring tool in melanoma patients.

Clinical significance of PCR-positive mRNA markers in peripheral blood and regional nodes of malignant melanoma patients. Melanoma Cooperative Group

Reverse-transcriptase polymerase chain reaction (RT-PCR) with multiple markers has been demonstrated to be highly sensitive in detecting metastatic cells in peripheral blood of malignant melanoma (MM) patients, and the circulating MM cells to be significantly correlated with disease stages. We further evaluated the presence of specific PCR-positive mRNA markers in peripheral blood as well as in regional nodes as an expression of tumor progression. Peripheral blood samples from 317 MM patients with either localized (n = 219) or metastatic (n = 98) disease were processed to obtain total cellular RNA. RT-PCR was performed using tyrosinase (TYR), p97, and MelanA/MART1 as mRNA markers. PCR products were analyzed by gel electrophoresis and Southern blot hybridization. In addition, paraffin-embedded samples of histologically proven tumor-negative lymph nodes from the subset of patients with localized disease were analyzed by RT-PCR, using radiolabeled primers for TYR and MelanA/MART1. The presence of mRNA markers was significantly correlated with tumor burden with a good correlation between risk of recurrence (evaluated in stage I-III patients) and increasing number of PCR-positive markers (p = 0.0002). Currently, for each patient, PCR results obtained at different times during follow-up are being analyzed, and any variation in the number of PCR-positive markers is being correlated to the clinical status. Molecular screening of histologically negative nodes for the presence of metastatic MM cells is also under evaluation. Preliminary assessment of a subset of MM patients with higher risk of recurrence will require longer follow-up in order to define the role of RT-PCR in monitoring these patients.